Ozone can come from a variety of sources, and often serves as an important component to a comprehensive water purification system. However, residual ozone represents a potential health hazard and it can be damaging to finished goods, as well as to processing and fabrication equipment. Using UV to remove ozone has an advantage because UV does not require additives that may leave behind residuals. In addition, dissociation of ozone with UV may also help to oxidize TOC’s.

Germicidal ultraviolet light destroys Ozone in water very quickly. Therefore, the 254 nm wavelength produced by low-pressure germicidal UV lamps is quite effective for ozone removal from water. The mechanism for removing ozone is dissociation, which occurs when 254 nm UV energy “breaks” one of the oxygen bonds in an ozone molecule. As a result of this reaction, each ozone molecule is converted into one oxygen atom and one oxygen molecule. Free oxygen atoms will combine with each other to form oxygen molecules.

Although ozone is readily destroyed by UV, it requires more UV energy than inactivation of microorganisms (approx 90 mJ/cm² versus 30 mJ/cm²). Therefore, in order to ensure effective ozone destruction, UV systems are often sized using a “flow-rate adjustment” of 40% the flow-rate of a disinfection system. For example, a system designed for 100 gpm disinfection flow-rate would be required to achieve 40 gpm for ozone destruction. This is only a approximation of the required UV. In actual situations, the amount of UV energy required is a function of flow rate, ozone concentration, UVT and the presence of other ozone consuming molecules.

UV ozone destruct (removal) is used in a wide range of industries such as food processing, biotechnology, pharmaceuticals, semiconductor fabrication, etc.

Because the process creates the hydroxyl radical as an intermediate in the removal of ozone, it is one of the main advanced oxidation processes.